Pharmacology (in Greek: pharmacon=drug, and
logos=science) is the study of how chemical substances interact with living
systems. If these substances have medicinal properties, they are referred
to as pharmaceuticals. The field encompasses drug composition, drug properties,
interactions, toxicology, and desirable effects that can be used in therapy
of diseases.

Development of medication is a vital concern
to medicine, but also has strong economical and political implications. To
protect the consumer and prevent abuse, many governments regulate the
manufacture, sale, and administration of medication. In the United States,
the main regulatory body is the Food and Drug Administration through its
publication of the USP.

Pharmacology as a science is practiced by
pharmacologists. Clinical pharmacology is the medical field of
pharmacology.

Scientific
background

The study of medicinal chemicals requires intimate
knowledge of the biological system affected. With the knowledge of cell biology
and biochemistry increasing, the field of pharmacology has also changed
substantially. It has become possible, through molecular analysis of enzymes,
to design chemicals that act on specific molecular pathways.

A chemical has, from the pharmacological
point-of-view, various properties. Pharmacokinetics is its fate (e.g. its
half-life and volume of distribution) in the organism, and pharmacodynamics
is its mode of action and potential toxicity.

When describing the pharmacokinetic properties
of a chemical, a pharmacologist employs the ADME principle:

* Absorption - How is the medication absorbed
(through the skin, the intestine, the oral mucosa)?

* Distribution - How does it spread through the
organism?

* Metabolism - Is the medication converted
chemically, and into which substances. Are these active? Could they be
toxic?

* Excretion - How is the medication eliminated
(through the bile, urine, skin)?

Medication is said to have a narrow or wide
therapeutic margin or therapeutic window. Those with a narrow window are
more difficult to dose and administer, and may require therapeutic drug
monitoring (examples are warfarin, some antiepileptics, aminoglycoside
antibiotics).

Classification

Medication can be usually classified in various
ways, e.g. by its chemical properties, mode of administration, or biological
system affected. An elaborate and widely used classification system is the
Anatomical Therapeutic Chemical Classification System.

The information above is not intended
for and should not be used as a substitute for the diagnosis and/or treatment
by a licensed, qualified, health-care professional. This article is licensed
under the GNU Free Documentation
License. It incorporates material originating from the Wikipedia article
"Pharmacology".